Technical Information

Domestic Water Systems

A tank containing debris (seen through the broken lid)

Domestic water systems provide water for drinking, washing and general domestic use. The water quality has to be acceptable in order to prevent risks to health such as Legionella, E.coli infections etc. Water supplied to buildings is generally of a good quality in the United Kingdom but there is a significant potential for deterioration once water is within a building. This can be caused by the presence of dead legs, usage below design for the building, uncovered tanks etc.

Pre-commission Cleaning

When a new building is constructed the domestic systems require disinfection after thorough flushing by the installing contractor but before being brought into use. BS6700.97 outlines the necessary procedure. The chemical used for the disinfection is usually sodium hypochlorite.

Following chlorination (disinfection) of the services, domestic water outlets need to be routinely used or flushed – for this reason it is best to wait until a few days before practical completion of the building before undertaking such works.

Chlorination of Operational Systems

Once a system is in use it may require chlorination if inspection of the associated tanks reveals debris to be present or microbiological counts in the water increase. In addition chlorination is required if the systems are altered.

Chlorination of operational systems is undertaken in accordance with L8 or BS6700:97.

In the event that domestic water systems become heavily contaminated, for example by vermin, or in the event that a heavy biofilm is present it may be necessary to undertake a more extensive scope of work using extended contact time or more aggressive chemicals.

Corroded pipework